I was wondering what weapon each hunter uses for each monster in MH3U? Because I know that there are preferred weapons for certain monsters (SA for Deviljho, Hammer for Rathian), so I was just wondering if people use the same weapons for the same monster or that it's still a matter of personal preference.

It seems that they bought down Greatswords a notch and buffed all other weapons to bring them out of niche roles. I noticed that ALL weapons can be used without GREAT deviation of effectiveness from monster to monster.

With that said, some weapons are more effective against monsters not because of vast differences in power (as it was the case in previous monster hunters), its due to the subtler nuances of the weapon such as attack speed, player mobility, the option to block, or weapon reach. The (re)addition of underwater combat also profounds this delicate balance.